These 2 charts basically tell the entire global demographic story

There are basically two big demographics stories in the world
right now:

The populations of emerging economies are young and growing,
while the populations of developed economies are aging and/or
shrinking.

You can see them both in the charts shared by HSBC's James
Pomeroy below, where India is proxy for the former and
Japan is a proxy for the latter.

HSBC

When it comes to emerging markets, countries like India, the
Philippines, and many in Africa have the populations
are large and young. And that means more demand and more
potential output in the near future.

(The one sort-of outlier here is China, which is starting to
see its working-age population shrink for the first time
ever. And although it has recently retired the one-child
policy, the impact from that won't be seen for some time.)

On the flip side,
developed economies have seen lower birth rates combined with
better health care for older folks, leading to populations
where there are more older people and less younger and
working-age folks. And that, opposite of the EMs, suggests that
there will be less demand and less potential output going
forward. In other words, the prospects for economic growth are
worse.

Alone, the developed economies' demographic story looks
kind of dim. But when you put the two trends
together, "the global demographic outlook is much better
than we may otherwise think, if we view the world as a global
labor market," notes Pomeroy in a recent note to clients.

Basically, emerging markets are growing at faster rates
than developed markets are shrinking, so the global population —
and thus, the global working-age population — is still
growing.If
you put developed and emerging markets together, global
population is expected to keep growing.HSBC

"However, most wealth is still in [developed markets] and the
biggest potential supply of labor is in
the [emerging/frontier] markets," he adds. "This mismatch
will need to be tackled if the [former's] pressing
demographic problems are to be addressed. Greater flows of
capital could be one solution and greater flows of people
another."

Interestingly, Europe's
migration crisis fits into this, as huge numbers of
people from emerging markets migrate into developed ones. And,
this has already had an effect on demographics stats. For
example: Germany's working-age population was forecast to fall by
4 million over the next decade, but it has now taken in
800,000-ish migrants, which is about 1% of
Germany's estimated population. Meanwhile, Sweden's
population is expected to grow 3% by the end of 2016 due to the
influx of migrants, "having huge repercussions for growth in the
near term," notes Pomeroy.

Nevertheless, it's important to add as an end note that more
people does not automatically translate to more laborers. There
are always issues with integration, which depends on things like
labor market flexibility, language skills, local political
agendas, etc.

And, to date, "there is considerable variety in the extent
to which different [European] countries have been able to
effectively integrate migrant workers in to the workforce and
employment,"
Citi's Tina Fordham previously noted.